Method of and apparatus for controlling the flow of liquid refrigerant into an expansion system



y 3 T. l. POTTER 2,079,253

METHOD OF AND APPARATUS FOR CONTROLLING THE FLOW OF LIQUID REFRIGERANT INTO AN EXPANSION SYSTEM Filed Jan. 26, 1931 5 //\/Z/E/\/7'U T. l. POTTER v Patented May 4, 1937 a 1 t v UNITED STATES PATENT OFFICE A METHOD OF AND APPARATUS FOR CON- TROLLING THE FLOW OF LIQUID REFRIG- ERANT INTO AN EXPANSION SYSTEM Thomas I. Potter, Portland, Oreg.

Application January 26, 1931, Serial No. 511,268

15 Claims. (ill. 62-3) This invention relates generally to mechanical Similar numbers of reference refer to similar refrigeration, and particularly to a method of and parts throughout the several views.

apparatus for controlling the flow of liquid re- Referring in detail to the drawing, inorder to frigerant into an expansion'system. illustrate this invention there is shown a com- 5 The main object of this invention is to propressor unit In including the usual operating mo- 5 vide a method of and apparatus for controlling tor ii and receiver if. A number of coolin the flow of liquid refrigerant into an expansion boxes it, It and i5 are also shown which, for the line, with special reference to small units in which sake of illustrating the inve are Shown indethe volume of refrigerant delivered to the evap- Den e t y of ac o ac of e Cooling l orator at any one period is exceedingly small. bOXeS l4 and is Provided With an expansion f 'Ihefsecomit object i? to provide a control system il Hi quii p d wit a t igz y ogg azi or re rigera ing uni s which have a numb r f expansion va ve e ower s1 0 expansion elements, which control will function lfllgnslifi valve ll iizcongfl tsg by mc g 2 Di properly regardless of the location of the ex- 150 8 e e W e eupper e 0 6940 Dansion elegnillllts orf the relative heat pumping valve l cg g 3 1 t gg 15 requiremen s ereo opposi esi e o eac co The third object is to provide a special form a p 9 t a pr su nt d swi hw, su of expansion valve for use in connection with as are m n y empl y n r fri r i tl'ge contrfol sy t m and the practice of the method ig h e n o 601 m s placed a frost line a ove re erre o. n eac xpa: s1 n l 1 2O Btefore entering into a description of this ing ge; h g ta ga lgv opera d 3 ven ion it must be understood that little diflla0 0X all S NOW 8 1 culty is experienced in controlling t flow of ond control switch 22 which is operated by box refrigerant from the high to the low pressure side temperatures- It W111 be undllrstood that the 3101': a system in large plants, due the relatively bOXFS M a 95 itnay Vary type m large volumelof reflrrigfirantdpassing through the $3 3 2 2 635 222 gr giggg 35 2 22 expansion va ve, w ic ren ers unnecessar extremely accurate adiustmenti The greatstydiffi operated interrupter 23 whose function it is to culty experienced is with small plants, especially ln'terrupt the flow ofhcurrent Whlch g :lo tlfiotsle employing anmonia, in which the volume g e igg g l g z g g fg gg g ga ii fiz w 22: o e s ream of re ri erant flowin throu h the n c valve is extremely smill, and in wliich th dimpasses in series through the pressure controlled culty of maintaining t small flo under y switch 20 and the motor] l, under the control of ing conditions increases rapidly as the volume dea a ually op Smtch From the t -1 if 11? fi f I i a 22thiiififtiifiiihlfii"2? 533 2 312283? 35 arge vo ume ow w c s eas 0 con ro, b l interrupt the flow for the purp se of decreasing provides means for varying Speed: the the total amount of refrigerant delivered in a motor a m l eq h f g z given amount of time. In other words, I deliver fAcross puma? p a ef;

the refrigerant to the expansion line in separate gggg' g g i gsg zigg gg gg 40 g g' g fiz i z or by means of a wire 28 The second side of each in errup ed ow ins ea 0 in a very sma s ream expansion valve ll 18 connected by means of 2.

whose regulation is very difiicult to maintain.

1 These, and other objects, will become more wire 29 to its respective frost ine control switch it. Each frost line control switch 2! is joined parent frm the speclfiqation fOlIOWiPg by a wire 3|] to its box and temperature control trated m the accompanymg drawmg' m Whlch: switch 22. Each box temperature control switch 1 is diagrammatic View of the entire 22 is connected by means of a wire 3| to one side y of the interrupter 23 whose opposite side is con- Fi 2 i a v rti a s i t r u h an l nected by means of a wire 32 to the trans- 50 trically operated expansion valve. former 21.

Fig. 3 is a section taken along the line 3-3 i Referring in detail to the electrical valve, same Fig. 2. will be seen to consist of an elongated tube 33 Fig. 4 is a perspective view of the core element upon Which is slidably mounted a solenoid coil forming a part of the expansion valve. 34 whose position on the tube 33 can be controlled 55 by means of a set screw 35. Within the tube 33 is placed a slidable core 36. The core 36 is provided with longitudinal grooves 31 on its sides between which are the communicating end grooves 38 at its lower end. In its upper end is inserted a hardened pin 39. A plug 40 closes the lower end of the tube 33 and receives its respective end of the refrigerant pipe |9. In the top of the tube 33 is inserted the valve body 4|. Into its lower end is formed a seat 42 in which lies the tapered end 43 of the plug 44 which contains a spring 45 whose tension can be regulated by a threaded plug 46 within the upper end of the body 4|. A cap 41 closes the upper end of the body 4| and receives its respective end of the pipe IS.

The operation of the device is as follows: Remembering that the operation of the compressor I0 is entirely under the control of the pressure actuated switch 20 and that the compressor will be operated by the switch 2!] whenever the pressure in the pipe |9 rises above a predetermined maximum, let us assume that the refrigerator is just being started, in which case all of the boxes I3, I 4 and I5 are warm and their respective frost lines I6 are warm. In this event the switches 2| and 22 are closed, permitting current to flow from the wire 28 through the coil 34 to the wire 3|. This flow of current is, however, interrupted by the interrupter 23 causing an intermittent energizing of the coil 34 and a successive raising of the core 33. This causes the pin 39 to strike against the under side of the plug 44 raising it from its seat and permitting a quantity of refrigerant to enter its respective expansion coil l6.

This operation will be continually repeated until the temperature of the coil l6 falls sufficiently to open its respective frost line switch 2|, thereby causing a cessation in the operation of the expansion valve l'l. However, as heat is drawn from the cooling box and absorbed by the coil 8 the switch 2| is again closed and the valve I! again operated. However, when the temperature of the box drops sufficiently to open the switch 22, this part of the circuit will not again be closed until both of the switches 2| and 22 are closed, by reason of the fact that there is too much heat at both of the locations.

While the operation at one of the cooling boxes alone has been described it is identical when any number of boxes are employed, it being entirely immaterial as to the operating range of temperatures or the amount of heat pumped from any given position.

It can be seen that by this system it is possible to accurately control the heat pumping action from a number of remote or separated points and to regulate the rate of heat absorption by varying the position of the coil 34 and the tension of the spring 45.

It will be noted that there are three possible ways of varying the flow of refrigerant through the expansion valve aside from that obtained by variation in the pressure carried on the low pressure side of the system. The first is accomplished by varying the tension of the spring, the second the position of the coil with relation to the core and last the number and/or duration of interruptions imposed on the circuit. Not only may these adjustments be made separately but with relation to each other, giving the utmost flexibility to the valve and making it possible to adapt same to a wide range of heat pumping requirements.

It will be seenfrom the foregoing that by this method extremely small quantities of refrigerant can be liberated in a given amount of time with the greatest amount of certainty that the amounts delivered will not be objectionably affected by the presence of moisture or foreign substance, or by changes in temperature or pressure within the related mechanisms.

I claim:

1. In a refrigerating machine, the combination of a condensing unit, and an expansion unit with means for intermittently admitting liquid refrigerant from the high side to the low side so that the refrigerant will flow in a pulsating stream, together with means for varying the effective cross-section of the opening in the intermittently operating means.

2. A method of controlling the flow of refrigerant into an expansion line consisting of establishing a pressure differential for the purpose of holding liquid refrigerant at a pressure over that in said expansion line, then liberating a pulsating stream of refrigerant to the lower pressure zone, and then relating the pressure of the refrigerant to the volume of flow and frequency of the pulsations in the manner to provide an aggregate delivery of the desired amount of refrigerant in a given period of time.

3. In a control for refrigerating systems, the combination of a pressure actuated motor con trolling switch, an electrically operated expansion valve adapted to liberate refrigerant into an expansion line, a temperature. actuated switch adapted to be closed by a rise in temperature in said line and connected in series with said electrically operated expansion valve, and means for interrupting the flow of current to said temperature actuated switch, said means comprising a compartment temperature switch adapted to be opened by a fall of temperature.

4. In a refrigerating system, the combination of an electrically driven refrigerating unit including a refrigerant line with a pressure actuated switch in the low pressure side of said refrigerant line adapted to cause the operation of said unit during over-pressures in said low pressure line, a cooling compartment associated with said refrigerating unit, an expansion coil in said compartment connected to said refrigerant line, an electrically operated expansion valve at the inlet end of said expansion coil, a frost line control switch on said expansion coil, a compartment temperature switch in series with said frost line control switch, and a coil associated with said expansion valve in series with both of said temperature switches.

5. In a refrigerating system, the combination of a refrigerant line, means for maintaining condensed refrigerant in a portion of said line, an intermittently operated expansion valve through which the condensed refrigerant must pass, an electrical coil for operating said valve, an interrupter in the coil circuit, and a pair of temperature actuated switches inseries with the coil circuit, one of said temperature switches operating under frost line temperatures and the other, under box temperatures to the end that an over-temperature at both the frost line and in the box will cause an operation of the expansion valve and an under-temperature at either the frost line or the box will stop the operation of said valve.

6. In a refrigerating system having a plurality of heat pumping zones, the combination of an electrically operated compressor unit having a refrigerant line connected thereto, each of said zones having an independent expansion line provided with an electrically operated expansion valve, and a dual control for said expansion valve consisting of a pair of temperature actuated switches in series with the operating mechanism of said valve, one of said temperature switches I closing under rises in the frost line temperature and the other under rises in the box temperature.

'7. In a refrigerating system, the combination of a pumping unit having a pressure actuated switch for controlling its operation and a plurality of cooling compartments from which heat may be drawn by said pumping unit, a pair of thermostatic switches in each compartment one of which is located near the frost line thereof and the other being disposed at a position for operation under compartment temperatures, separate expansion means between each compartment and the pumping unit, and electrically operated expansion means connected in series with said thermostatic switches for the purpose of stopping the operation of said expansion means when either of said thermostatic switches opens the circuit due to a local drop in temperature and causing said expansion means to be operated when both of said thermostatic switches are. closed by over-temperatures at their respective locations.

8. In a refrigerating machine the combination of a condensing unit, an expansion unit, a refrigerant line connecting said units in a closed cycle, an expansion valve in the line for admitting refrigerant from the condensing unit into the expansion unit, an actuator for rhythmically opening and closing said valve at a predetermined frequency so as to pulsate the flow of refrigerant into the expansion unit, and means for regulating the extent of opening of the valve.'

9. In a refrigerating machine the combination of a condensing unit, an expansion unit, a refrigerant line connecting said units in a closed cycle, an expansion valve in the line for admitting refrigerant from the condensing unit into the expansion unit, an actuator for rhythmically opening and closing said valve at a predetermined frequency so as to pulsate the flow of refrigerant into the expansion unit, and means,

for regulating the duration of openings of the valve during such pulsating flow.

10. In a refrigerating machine the combination of a condensing unit, an expansion unit, a refrigerant line for supplying a stream of liquid refrigerant to said expansion unit, means for controlling periods of flow of the refrigerant into said expansion unit, an interrupter for sub-dividing the fiow during each period, and means for varying the frequency of the interrupter.

11. In a refrigerating machine the combination of a condensing unit, an expansion unit, a refrigerant line for supplying a stream of liquid refrigerant to said expansion unit, means for controlling periods of flow of the refrigerant into said expansion unit, an interrupter for subdividing the fiow during each period into a series of slugs of refrigerant, and means for varying the time intervals between successive slugs.

12. In a refrigerating machine the combination of a condensing unit, an expansion unit, a refrigerant line for supplying a stream of liquid refrigerant to said expansion unit, means for controlling periods of flow of the refrigerant into said expansion unit, an interrupter for subdividing the fiow during each period into a series of slugs of refrigerant, and means for varying the volume of each slug and the time interval between successive slugs.

13. In a refrigerating machine the combination of a condensing unit, a pair of expansion units,

14. In a refrigerating machine the combination I:

of a condensing unit, an expansion unit, a supply of liquid refrigerant, means for rhythmically connecting and disconnecting the expansion unit directly to and from said supply so as to provide a pulsating flow into the expansion unit, and means for varying the frequency of the pulsations so as to provide an aggregate delivery into the expansion unit of a desired amount of refrigerant in any given period of time.

15. In a refrigerating machine, the combination of a condensing unit, an expansion unit, and means for intermittently admitting liquid refrigerant from the high side to the low side so that the refrigerant will flow in a pulsating stream, said means comprising an admission valve opening from the high side directly into the low side and adjustable operating means for said valve controlling the extent to which the valve is opened at each operation thereof. THOMAS I. POTTER. 

